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Continuous monitoring of thermal solar panels’ efficiency


The proper operation of thermal solar panels (TSP) is an issue as the maintenance (if any, in most of the cases: none) is usually performed once a year. The deterioration of the installation is not apparent to the owner as TSP is only a supporting system. In fact, Domestic Hot Water (DHW) is still available, but the heating energy needed rises because the inflow of (cold) water is not pre-heated by the solar system.

There are above 25’000 villas in Geneva and in Switzerland above 1 million (according to Statistic Office of Swiss Confederation). There is no specific data on villa equipped with TSP but at least 10% should. Laws on energy’s efficiency has already been passed in some cantons. This will further push the installation of such systems.


  1. Define the 5 to 7 key parameters and their weighting to calculate the rated efficiency of the TSP installation (orientation, angle, cleanliness, shadows age, glycol quality, etc.) so that it can be compared with actual production. (Producer data are far too optimistic as they are obtained in laboratories).
  2. Put together the necessary low-cost kit to allow continuous data monitoring able to detect deterioration of the TSP’s efficiency. This kit should not cost more than 500 CHF (without installation)
  3. Define the business model to enter into the villa market and define a USP for the residential building. The revenue model should derive from yearly contract revenue. The automated data management should allow to have a low annual fee (almost no variable cost) and the business development should come from volume. To get this volume in a reasonable time it is important to define the adequate distribution model.

Data Management

Collected data will be directed to already existing SCADA system (Ignition). This system allows data management, alarm algorithms and automated reporting.

Technical pre-requisites

  • A sample of 20 installations should be sufficient to get a fair approach to rated efficiency
  • The low cost kit should be composed of:
    • Gateway (Mbus or LoRawan)
    • Water meter with Mbus or LoRawan
    • Interface to solar control unit